I know I'm not the only one who's had this problem so I decided to post the fix I came up with for it.

When shutting down the computer it seems that dhcpd doesn't delete the /etc/dhcpc/dhcpcd-eth0.cache file so when you start the computer again dhcpcd doesn't assign an IP for the NIC so there is no network access.

In /etc/rc.d/rc.6 I added these two lines :

sleep 5
rm /etc/dhcpc/dhcpcd-eth0.cache

just below the line to kill dhcpcd.

The sleep 5 is to allow dhcpcd time to shut down. Probably overkill as sleep 1 or sleep 2 is probably long enough, but I went with 5 to be sure.

Obviously the following line deletes the offending file.

Now my NIC comes up with a dhcp assigned IP every boot up.

Hope maybe this helps someone.

I suppose that works, though the cache file is supposed to keep a record of old leases that may still be valid to reduce load on the DHCP server... i'm not sure why it wasn't reassigning, even with that.